Rose Breeding for the New Millennium

Thromas Proll, director of the breeding department at Kordes Roses will speak on the above subject at 8:00 pm Thursday September 13, at the Royal Botanical Gardens Centre, Rooms # 1 and #2 in Burlington, Ohio. Reservations are required due to limited seating. There is a fee of $5.00 to help cover room rental.

The e-mail address given is or call 905-335-0399.

The above is taken from “The CRS COMMPOSTER” volumn IV, No. 3, August 2007. The newsletter of the Canadian Rose Society.

Oh man, 30 mins from home!!! I’m a huge fan of Kordes and I have absolutely no excuse for not going. Henry, thank you for posting this. Liz

I was just chatting with Joyce Flemming as she will be in attendance. I met her at Descanso Gardens a couple of seasons ago.

I’m a fan of Kordes too. I wish I could attend. Please tell her I said hello.

wow, I wish I wasn’t in school. But I might be able to see some London gardens this spring… still, Kordes is one of my faves. I was so sad when McGredy retired cause I like both producers of roses.

What a great topic. Darn, wish I lived closer.

Good to know that Joyce will be there. She is even closer to RBG than I am. Robert, I’ll definitely say hi to her from you.


As Peter Harris pointed out in an e-mail, it should say Burlington, Ontario (not Ohio).

Sounds great! Hopefully, someone can give a brief synopsis of the talk, as it should be very interesting.

Jim Sproul

Anyone else able to go to the talk this evening??


Well it was a great 2+ hours of listening to Thomas Proll. He apparently will be giving an abreviated version of this talk at the ARS fall meetings in St. Louis. He was in Ontario visiting Palatine. The talk was split into 2 parts, part 1 being a brief history of the company followed by a presentation of their breeding process. The second half of the talk he focused on the more recent (2004/05 onward) roses of theirs that have received the ADR designation. Hopefully my notes are correct.

So the breeding overview, he only talked about what they do for the garden roses. All crossing is done indoors starting April/May and going for about 6-7 wks. The parents are grown in 40L pots and they routinely have about a 30% turnover of parents each year. They use 400-500 pollen parents. I missed the number of seed parents, but there is 1400 pots of them with 2-3 plants/pot. They will make about 100,000 pollinations, representing ~2000 unique combinations, and resulting in 60-80,0000 hips (~800,000 seeds). Their average germination rate works out to about 50%.

They do not place the seeds in cold, rather they plant them in benches in their greenhouses and keep the temps between 2-4 C. Germination starts in Jan. Less than 10% of the seedlings will make it out of the greenhouse, those that do are immediately budded onto 3 rootstocks. This is generally around 10,0000 seedlings which are grown in their 3-plant field trial in year 2. In years 3-4, those that have survived selection (~1000 seedlings) are now grown in a 10-plant group field trial. Years 5-6, there are roughl;y 250 seedlings left and are grown in a 100-plant group field trial. By year 7 there are perhaps 10 seedlings left and they have 1000-plant groups of each of them. At this stage they will send about half of them to rose trials. By the mass propagation stage, years 8-10 they are down to 5-7 varieties and ~25,000 plants/yr of each. So they are looking at a 10 year window from crossing to commercial release of a named variety.

Breeding objectives - #1 goal is disease resistance, #2 is cold (frost) hardiness, #3 is heat tolerance, #4 is flowering abilities, #4 is flowering characteristics, #5 is growth characteristics, #6 ability to propagate on own roots, and #7 is cultivation in containers.

As I mentioned in the going native post, in 1990 Kordes stopped spraying for disease period. He showed a photo from the fields in 1990 and it was mostly just sticks, but there were a few plants that looked healthy. To contrast this he showed a recent photo of their trial fields and you would have a hard time picking out the sticks. The ADR trials are also no-spray, although I do not know when this practice was put into place.

So when he was talking about the more recent ADR lines I was trying to keep track of which ones he really stressed. Grand Amore, Eliza, Escimo, Golen Gate, Lions Fairy Tale, Kosmos, Pomponella, Jasmina (which is 1/2 rambler), Lupo (used for hip production) Aprikola was also heavily stressed. And at one point he did talk about Westerland being in the parentage of one of the roses, but for the life of me I do not remember which one.

Just as an aside, he spoke quite favorably about their competitor Noack’s efforts in developing disease resistant roses. Spoke about the difference in what the buying public in Germany and Europe wants vs. North America. Spoke about what Rosarians like/appreciate vs. the general buying public. And several times stressed the importance to the industry in developing roses that will shatter the perception that roses are difficult plants to grow.

Wonderful Liz. Thank you for this.

Great information Liz. Thank you.

As an aside, I wish Kordes would list parentage for their new introductions instead of listing it as undisclosed.

Robert, Joyce Fleming returns your “Hi”. She and I walked out together and she too really wishes that they would disclose their parentage. Thomas did imply that many/all of the roses that made it through to the later stages of selection were used as parents.

Dear Liz, a sincere thank you for the detailed report on Mr. Proll’s presentation - quite informative.

I wonder if Mr. Proll elaborated on what he meant by disease resistance. I ask because this terminology is used quite loosely. Out of confusion/frustration, I and two others wrote an article ‘MUSINGS ABOUT BLACK SPOT RESISTANCE IN WINTER-HARDY ROSES’ published in The Canadian Rose Annual (2005) pages: 73-78 and proposing a possible scenario for a way out of this dilemma for hardy roses.

It seems to me that black spot (BS) and roses go together and no matter what one crosses sooner or later even the most resistant roses exhibit signs of BS whether due to mutation of spores or the introduction of new spores etc. An example is ‘William Baffin’ (WBA) which is highly resistant to this fungal disease develops some BS in late August or early September in Green Valley, Ontario. ‘William Booth’ (WB) another highly resistant rose develops more BS than WBA. It should be noted that there is excellent air flow in the area of these roses and little that would contribute to this disease.

Perhaps the solution to BS and other fungal diseases of roses is to develop safe EFFECTIVE biological spray(s). One which will interrupt the development cycle of BS and other fungal diseases. Since nature is always in a state of flux, the battle against BS will continue. Gene insertion may solve the problem but I prefer not to go there.

I note that cold hardy means frost resistance. Cold hardy in Green Valley, ON refers to a rose which will resist (-40F) including wind chill.

Further, to avoid confusion the terms used could be qualified with a definition.

Perhaps others may have their own ideas on this subject.

Your options for growing roses in -40F must be limited Neville. Could you name a couple that you are working with that withstand such temps? Thank you.


I have made this statement a number of times on a number of forums. I do not consider blackspot appearing on roses in the fall as a problem. I consider it part of nature’s plan to prepare the roses for winter.

Disease by fall doesnt bother me any since I obviously am just going to winter prune soon after dormancy anyways. However, it must suck for southerners, lol.

Okay, that settles it. Im getting Grand Amore. I couldnt decide if I wanted to order it for 2008, but now I know Im curious. Thanks, Liz!

Thank you, Liz, for the summary of the presentation. I also attended a similar presentation by Thomas Proll. It was held last year in Belgium.

About the parentage: like I wrote in the Going native thread, the parentage can be found in the patent information. However, they do use a lot of unnamed seedlings and the lineage of these seedlings is not recorded in the patent info. I sent my findings from yesterday to Helpmefind.

Golden Gate is a grandchild from Westerland. It is ‘Postillion x seedling’ and Postillion is ‘Westerland x Lichtkonigin Lucia’.

Because of the difference you mention between the current Kordes seedling beds and those in the early nineties I believe that we cannot simply attribute the disease resistance of the Kordes roses as results of ‘lottery’ only. The difference shows that their breeding strategy clearly plays a role in their accomplishment of finding disease resistant varieties. This is why I also believe that we can also use resistant modern roses as a source of disease resistance for our own seedlings, even though we do not raise 200.000 seedlings each year.


To the scepticals about desease resistance breeding: just grow an average HT cross progeny without spraying and you will understand. Even with favoured climate most nice seedlings are more desease prone than the cross parents. To the point some crosses are complete failures.